Adsorption of Aldehyde-Functional Diblock Copolymer Spheres onto Surface-Grafted Polymer Brushes via Dynamic Covalent Chemistry Enables Friction Modification

被引：7

作者：

Johnson, Edwin C. ^{[1
]}

Varlas, Spyridon ^{[1
]}

Norvilaite, Oleta ^{[1
]}

Neal, Thomas J. ^{[1
]}

Brotherton, Emma E. ^{[1
]}

Sanderson, George ^{[2
]}

Leggett, Graham J. ^{[1
]}

Armes, Steven P. ^{[1
]}

机构：

[1] Univ Sheffield, Dept Chem, Dainton Bldg,Brook Hill, Sheffield S3 7HF, England

[2] GEO Specialty Chem, Southampton SO45 3ZG, England

来源：

CHEMISTRY OF MATERIALS | 2023年 / 35卷 / 15期

基金：

英国工程与自然科学研究理事会;

关键词：

PH; NANOPARTICLES; NETWORKS; FORCES; ORGANIZATION; ACTIVATION; PARTICLES; LIGANDS; SILICON; BASE;

D O I：

10.1021/acs.chemmater.3c01227

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

Dynamic covalent chemistry has been exploited to preparenumerousexamples of adaptable polymeric materials that exhibit unique properties.Herein, the chemical adsorption of aldehyde-functional diblock copolymerspherical nanoparticles onto amine-functionalized surface-graftedpolymer brushes via dynamic Schiff base chemistry is demonstrated.Initially, a series of cis-diol-functional sterically-stabilizedspheres of 30-250 nm diameter were prepared via reversibleaddition-fragmentation chain transfer (RAFT) aqueous dispersionpolymerization. The pendent cis-diol groups withinthe steric stabilizer chains of these precursor nanoparticles werethen oxidized using sodium periodate to produce the correspondingaldehyde-functional spheres. Similarly, hydrophilic cis-diol-functionalized methacrylic brushes grafted from a planar siliconsurface using activators regenerated by electron transfer atom transferradical polymerization (ARGET ATRP) were selectively oxidized to generatethe corresponding aldehyde-functional brushes. Ellipsometry and X-rayphotoelectron spectroscopy were used to confirm brush oxidation, whilescanning electron microscopy studies demonstrated that the nanoparticlesdid not adsorb onto a cis-diol-functional precursorbrush. Subsequently, the aldehyde-functional brushes were treatedwith excess small-molecule diamine, and the resulting imine linkageswere converted into secondary amine bonds via reductive amination.The resulting primary amine-functionalized brushes formed multipledynamic imine bonds with the aldehyde-functional diblock copolymerspheres, leading to a mean surface coverage of approximately 0.33on the upper brush layer surface, regardless of the nanoparticle size.Friction force microscopy studies of the resulting nanoparticle-decoratedbrushes enabled calculation of friction coefficients, which were comparedto that measured for the bare aldehyde-functional brush. Frictioncoefficients were reasonably consistent across all surfaces exceptwhen particle size was comparable to the size of the probe tip. Inthis case, differences were ascribed to an increase in contact areabetween the tip and the brush-nanoparticle layer. This new model systemenhances our understanding of nanoparticle adsorption onto hydrophilicbrush layers.

引用

页码：6109 / 6122

页数：14